In Children, Reduced Arousal Aggravates Respiratory Depression By Morphine
SEATTLE, WA—Reporting on a study of the reaction of children to morphine administration at SLEEP 2015, Gaspard Montandon, PhD, from the University of Toronto, said that respiratory depression was “more severe when patients were in states of reduced arousal due to the sedative properties of morphine.”
Opioid analgesics are widely used in the hospital setting to alleviate pain. In addition to their analgesic properties, opioids also induce sedation and depress breathing. Because breathing is modulated by brain arousal, sedation by opioids may further depress breathing. Dr. Montandon and colleagues set out to evaluate the effect of opioid medication on electroencephalogram (EEG) and respiration in children following ear surgery. The participants were recruited from the ENT clinic.
“Although opioid drugs have potent side effects, our understanding of their mechanisms of action on arousal, sleep and respiratory systems is limited, especially in young patients who are more sensitive to opioid drugs,” Dr. Montandon noted.
“Following surgery, as per standard clinical care, the participants stayed overnight for pain relief (morphine), hydration, and clinical observation,” he stated. To evaluate their response to morphine, a polysomnogram was performed the night after surgery. Data were processed to extract EEG spectral properties and respiratory activity and compared before (baseline) and after nighttime administration of morphine.
A total of eight children ranging in age from 4–18 years received morphine. The children had no known respiratory disorders, no planned airway surgery, and no chronic use of opioid therapy. The morphine dose ranged between 5–10mg; the average dose was 0.17±0.04mg/kg.
When data before and after morphine administration were compared, “we observed that morphine reduced arousal and induced a sedative state similar to slow-wave sleep. This state of reduced arousal was characterized by increased low electroencephalogram (EEG) frequencies and decreased high frequencies,” Dr. Montandon stated. While respiratory depression intensifies with increases morphine dose, there appeared to be a correlation with age.
Dr. Montandon concluded, “Sedation by morphine also induces a shift of power from frontal to dorsal EEG.”